Description: (Taken directly from the application) To facilitate whole animal experimental approaches for projects associated with the PKD Center, the existing Case Western Reserve Mouse Mutation Laboratory will be expanded to accommodate the needs of Center investigators. Embryonic stem (ES) cell culture and blastocyst/pronuclear injection techniques are labor intensive, requiring specialized training and expensive equipment. The Core laboratory will centralize these duties, thereby making it more productive and cost efficient. In addition, the Core will re-derive, cryopreserve and manage the breeding of mutant colonies needed for the various projects. The facility will be responsible for: 1. Re-derivation and cryopreservation of imported lines 2. Centralized breeding, maintenance and storage of all mutant lines either made by the facility or imported from other sources of mutant colonies as well as production of double mutants 3. Pronuclear injections to produce transgenic mice 4. Characterization and maintenance of diploid, germ line competent ES cells 5. Electroporation and selection to identify targeted clonal lines 6. Karyotype analysis of targeted lines 7. Blastocyst injections to produce germ line chimeras 8. Consultation with Principal Investigators regarding breeding schemes, construct design and experimental strategy